1. Field of the Invention
The present invention relates to a pulse signal generator and a method of making the same.
2. Description of the Related Art
It is necessary in some automatic control or electric and electronic equipment to generate a pulse signal corresponding to the position or speed of a moving object or responsive to various operations. An example of the conventional pulse signal generator is a revolution detector by means of an electromagnetic/optical pick-up or Hall/magnetic reluctance element. The electromagnetic type, however, provides low output power in the range between 0 and low-speed revolutions. The optical pick-up system requires a broadband d-c amplifier and a dust proof structure. The Hall/reluctance system needs a plurality of elements and an amplifier. In addition, the optical pick-up, up, Hall, and reluctance systems employ an element that is too sensitive to temperature to use in the environment that experiences large temperature changes.
Consequently, these revolution detectors are not able to detect the revolution speed or position of an engine crank or cam shaft for very low- to high-speed revolutions. In addition, they are not suitable for use in an automobile that experiences wide temperature changes and noise.
Japanese patent application Kokai Nos. 2000-101400 and 101401 disclose a pulse signal generator employing a magnetic element wire that is able to cause the large Barkhausen jump. The pulse signal generator of this type is free from the above problems, but it still needs improvements for use in automobiles. For example, it must be versatile in terms of installation in the limited space of an automobile. Such a limited space varies with the positions of engine and other associated parts of each car model. In order to provide accurate detection, it is necessary to install the pulse signal generator at the right position relative to the object to be detected. Thus, the versatility of the generator in terms of installation is essential.
Accordingly, it is an object of the invention to provide a pulse signal generator that is versatile for installation and a method of making such a generator.
According to an aspect of the invention there is provided a pulse signal generator which comprises a detection assembly including a magnetic field generating unit and a magnetic element wire able to cause a large Barkhausen jump responsive to movement of an object to be detected; a case for housing said detection assembly; an attaching section for attaching said case; and a positioning guide provided on an inside surface of said case for positioning said detection assembly at a desired angular position with respect to said object.
According to an embodiment of the invention, the attaching section is molded integrally with said case as a unit and said positioning guide is molded integrally with said case at a predetermined angular position with respect to said attaching section.
According to another embodiment of the invention, the case is rotatable with respect to said attaching section and said detection assembly is locked at a desired angular position with respect to said attaching section.
According to another aspect of the invention there is provided a method of making the pulse signal, comprising the steps of providing an upper half mold having an upper half mold cavity for defining an upper half of an outer surface of said case and a lower half mold having a lower half mold cavity for defining a lower half of said outer surface, and a rotatable mold for defining an inside surface of said case; closing said upper and lower half molds such that said rotatable mold is rotated to a desired angular position to form an annular mold cavity between said upper and lower half molds and said rotatable mold; pouring a mold material into said annular mold cavity to form said case; and installing said detection assembly in said case.